Determination of γ-Aminobutyric Acid in Lepidium meyenii. Walp (Maca) and the Factors Affecting Its Content
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Abstract:
Maca (Lepidium meyenii. Walp) was used as the experimental material in this study to establish a method for the detection of its active ingredient, γ-Aminobutyric acid (GABA). Using an amino acid analyzer, the effects of the place of origin, color type, and glutamic acid, proline, and crude fiber content on the GABA content in maca were analyzed. The results showed that the content of GABA in maca could be rapidly determined using an automatic amino acid analyzer with a K06 LCA sodium ion chromatography column (4.6 mm×150 mm, 7 μm). The column temperature was maintained at 58 ℃ and the reactor temperature was maintained at 130 ℃. The flow rates of the elution and derivative pumps were 0.45 and 0.25 mL/min, respectively, and detection was performed at 570 nm and 440 nm. The gradient elution program was as follows: 0~1.0 min, 30% A and 70% B; 1.0~9.0 min, 100% B; 9.0~12.0 min, 100% D; 12~14 min, 100% A. Under natural conditions, GABA was found to accumulate in maca. The GABA content in maca was not obviously influenced by color type, was significantly affected by the place of origin (p<0.05), and was significantly positively correlated with proline. Meanwhile, the GABA content had a weak negative correlation with glutamic acid and a positive correlation with crude fiber, but neither were significant (p>0.05). Maca is a plant resource with high GABA content, and the environment of the place of origin was shown to have a significant effect on the content of GABA; hence, selection of appropriate cultivation conditions to accumulate GABA in maca is required.
